It is known that there are large differences in the morphology of the vertebrate heart: from the Cyclostome and fish hearts with its single atrium and single ventricle to the bird and mammalian hearts with two fully separated atria and ventricles. At present it is necessary to revise the data on the topography of the atrial pacemakers in the vertebrate heart. Pacemaker cells have some specific electrophysiological properties that make them different from atrial working myocardium and conducting cells. In this study, we aimed to establish a functional topography of the pacemaker cardiomyocytes in the isolated sinoatrial and atrioventricular areas of the heart in different representatives of vertebrates: lamprey (Lethenteron japonocum), carp (Carassius carassius L.), frog (Rana temporaria L.), lizard (Lacerta vivipara L.), chicken (Gallus gallus domesticus), pigeon (Columba livia L.), mouse (Mus musculus) and cat (Felis catus L.), using microelectrode mapping of action potentials (APs). All experimental procedures conformed to the Guide for the care and use of laboratory animals published by the US National Institutes of Health (NIH publication No. 85-23, revised 1985). It was found that in the lamprey, carp, frog and lizard hearts APs of pacemaker cells were recorded from the base of leaflets of sinoatrial and atrioventricular valves. In the chicken and pigeon hearts sinoatrial pacemaker is localized in the base of the right sinoatrial valve. In the atrioventricular area pacemaker cells are embedded in fibrous tissue and located near the base of the right muscle atrioventricular valve and in the region of the coronary sinus. In the mouse and cat hearts, cells with pacemaker activity are distributed in the region of the mouth of the superior vena cava, in the area adjacent to the coronary sinus and also in the base and in the leaflets of the atrioventricular valves. In the studied animals the maximal depolarization rate of pacemaker APs in the sinoatrial area increases in the anterograde direction, while their APs duration decreases. In the atrioventricular area the reverse regularity of the APs parameters distribution is observed. Thus the areas of the valves are supposed to be specific places of pacemaker cells localization in the Cyclostome, fish, amphibian, reptilian, avian and mammalian hearts. The data obtained indicate the conservatism of the evolution of cardiac pacemakers.